Pipes, systems, and methods for transporting hydrocarbons

ABSTRACT

There is disclosed a method of transporting a produced fluid through a pipe while limiting deposits at a desired pipe inner-wall location comprising providing a pipe having an inner surface roughness Ra less than 2.5 micrometers at said desired pipe inner-wall location, forcing the produced fluid through the pipe, wherein the produced fluid has a wall shear stress of at least 1 dyne per centimeter squared at said desired pipe inner-wall location.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application60/643,320 filed on Jan. 12, 2005, having attorney docket number TH1043.This application claims priority to U.S. Provisional Application60/715,250 filed on Sep. 8, 2005, having attorney docket number TH2733.U.S. Provisional Application 60/715,250 and 60/643,320 are hereinincorporated by reference in their entirety.

FIELD OF INVENTION

There is disclosed pipes, systems, and methods for transporting producedfluids from one or more wells, more particularly, there is discloseddeposit-growth retarding pipes, systems, and methods for transportingwell production streams.

BACKGROUND

As produced fluid is transported through pipes in an environment thatcools the fluid, for example to temperatures less than 5° C., forcertain types of produced fluids, deposits may form on pipeline walls.Some of these deposits may be, for example, wax deposits as the waxsolidifies due to the cold temperatures or gas hydrates. Such walldeposits serve to reduce the efficiency of the pipeline because theyblock part of the pipeline opening, and reduce the flow rate of theproduced fluid and/or increase the pressure in the pipeline. Numeroussolutions to the problem of pipeline deposits have been proposed. Onesolution is a heated pipeline, which serves to keep the oil flowingthrough the pipeline above the temperature at which solids would form.Patents have been issued to Shell Oil Company in the area ofelectrically heated pipelines, which solve this problem.

Another solution to the problem of deposits on a pipeline wall is toinsulate the pipeline to keep the crude oil at an elevated temperature.

It is desired to avoid the problem of deposition on a pipeline wall.

In the cases that deposits are not avoided, it is desired that thedeposits be easily removed by a pig.

In the cases that use pigs to remove deposits, it is desired that thepigged stream be a slurry of pigged deposits and produced fluid.

SUMMARY OF THE INVENTION

One aspect of invention provides a method of transporting a producedfluid through a pipe while limiting deposits at a desired pipeinner-wall location comprising providing a pipe having an inner surfaceroughness Ra less than 2.5 micrometers at said desired pipe inner-walllocation, forcing the produced fluid through the pipe, wherein theproduced fluid has a wall shear stress of at least 1 dyne per centimetersquared at said desired pipe inner-wall location.

Advantages of the invention include one or more of the following:

transport of produced fluids with significantly reduced deposits;

transport of produced fluids without deposits;

a reduced force required for pigging; and

generation of a fluid slurry when pigging.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of a platform and a satellite subsea well connected bya subsea pipeline.

FIG. 2 is a side cross-sectional view of a pipeline.

FIG. 3 is an end cross-sectional view of the pipeline of FIG. 2.

FIG. 4 is a side cross-sectional view of a pipeline.

FIG. 5 is an end cross-sectional view of the pipeline of FIG. 4.

FIG. 6 is a side cross-sectional view of a pipeline.

FIG. 7 is a side cross-sectional view of a pipeline.

FIG. 8 is a view of a smooth pipe with a deposit.

FIG. 9 is a view of a standard-roughness pipe with a deposit.

FIG. 10 is a plot of surface roughness Ra for four different pipes.

FIG. 11 is a plot of Rti distribution for four different pipes.

FIG. 12 is a plot of the angle distribution for four different pipes.

FIG. 13 is a deposition map as a function of roughness and wall shearstress.

FIG. 14 is a plot of pressure drop across a pig.

DETAILED DESCRIPTION

In one embodiment, there is disclosed a pipe adapted to transport crudeoil, the crude oil having a temperature less than 65 C in at least aportion of the pipe, wherein the pipe comprises a surface roughness lessthan 0.025 mm. In some embodiments, the crude oil has a temperature lessthan 55 C. In some embodiments, the crude oil has a temperature lessthan 38 C. In some embodiments, the surface roughness is between 0.025mm and 0.0025 mm. In some embodiments, the surface roughness is between0.025 mm and 0.01 mm. In some embodiments, the surface roughness isbetween 0.01 mm and 0.0025 mm.

In one embodiment, there is disclosed a system for producing andtransporting crude oil, comprising a well for producing the crude oil; aprocessing facility for processing the crude oil; and a pipeline fortraversing at least a portion of the distance between the well and theprocessing facility, wherein at least a portion of the pipeline travelsthrough an atmosphere having a temperature less than 20 C, wherein thepipeline comprises a surface roughness on its interior surface less than0.025 mm. In some embodiments, the atmosphere has a temperature lessthan 15 C. In some embodiments, the atmosphere has a temperature lessthan 10 C. In some embodiments, the surface roughness is between 0.025mm and 0.0025 mm. In some embodiments, the surface roughness is between0.025 mm and 0.01 mm. In some embodiments, the surface roughness isbetween 0.01 mm and 0.0025 mm.

In one embodiment, there is disclosed a method of producing andtransporting crude oil, comprising extracting crude oil from a well;placing the crude oil in a pipeline to transport the crude oil away fromthe well; wherein at least a portion of the pipeline travels through anatmosphere having an ambient temperature less than 20 C; and wherein thepipeline has a surface roughness less than 0.025 mm on an interiorsurface. In some embodiments, the atmosphere has a temperature less than15 C. In some embodiments, the atmosphere has a temperature less than 10C. In some embodiments, the surface roughness is between 0.025 mm and0.0025 mm. In some embodiments, the surface roughness is between 0.025mm and 0.01 mm. In some embodiments, the surface roughness is between0.01 mm and 0.0025 mm.

In one embodiment, there is disclosed a system for producing andtransporting crude oil, comprising a well means; a processing means; anda pipeline for connecting the well means with the processing means; atleast a portion of the pipeline traveling through an atmosphere havingan ambient temperature less than 20 C; and a means for reducing thesurface roughness on an interior surface of the pipeline. In someembodiments, the atmosphere has a temperature less than 15 C. In someembodiments, the atmosphere has a temperature less than 10 C. In someembodiments, the means for retarding comprises a surface roughness lessthan 0.025 mm. In some embodiments, the surface roughness is between0.025 mm and 0.01 mm. In some embodiments, the surface roughness isbetween 0.01 mm and 0.0025 mm.

In one embodiment, there is disclosed a method of transporting aproduced fluid through a pipe while limiting deposits at a desired pipeinner-wall location comprising providing a pipe having an inner surfaceroughness Ra less than 0.5 micrometers at said desired pipe inner-walllocation, forcing the produced fluid through the pipe, wherein theproduced fluid has a wall shear stress of at least 1 dyne per centimetersquared at said desired pipe inner-wall location.

In one embodiment, there is disclosed a method of transporting aproduced fluid through a pipe while limiting deposits at a desired pipeinner-wall location comprising providing a pipe having an inner surfaceroughness Ra less than 1 micrometer at said desired pipe inner-walllocation, forcing the produced fluid through the pipe, wherein theproduced fluid has a wall shear stress of at least 20 dyne percentimeter squared at said desired pipe inner-wall location.

In one embodiment, there is disclosed a method of transporting aproduced fluid through a pipe while limiting deposits at a desired pipeinner-wall location comprising providing a pipe having an inner surfaceroughness Ra less than 1.5 micrometers at said desired pipe inner-walllocation, forcing the produced fluid through the pipe, wherein theproduced fluid has a wall shear stress of at least 100 dyne percentimeter squared at said desired pipe inner-wall location.

In one embodiment, there is disclosed a method of transporting aproduced fluid through a pipe while limiting deposits at a desired pipeinner-wall location comprising providing a pipe having an inner surfaceroughness Ra less than 2.5 micrometers at said desired pipe inner-walllocation, forcing the produced fluid through the pipe, wherein theproduced fluid has a wall shear stress of at least 400 dyne percentimeter squared at said desired pipe inner-wall location.

In one embodiment, there is disclosed a method of transporting aproduced fluid through a pipe while limiting deposits at a desired pipeinner-wall location comprising providing a pipe having an inner surfaceroughness angle root-mean-square of less than 5 degrees at said desiredpipe inner-wall location, forcing the produced fluid through the pipe,wherein the produced fluid has a wall shear stress of at least 1 dyneper centimeter squared at said desired pipe inner-wall location.

In one embodiment, there is disclosed a method of transporting aproduced fluid through a pipe while limiting deposits at a desired pipeinner-wall location comprising providing a pipe having an inner surfaceroughness angle root-mean-square of less than 6 degrees at said desiredpipe inner-wall location, forcing the produced fluid through the pipe,wherein the produced fluid has a wall shear stress of at least 20 dyneper centimeter squared at said desired pipe inner-wall location.

In one embodiment, there is disclosed a method of transporting aproduced fluid through a pipe while limiting deposits at a desired pipeinner-wall location comprising providing a pipe having an inner surfaceroughness angle root-mean-square of less than 7 degrees at said desiredpipe inner-wall location, forcing the produced fluid through the pipe,wherein the produced fluid has a wall shear stress of at least 100 dyneper centimeter squared at said desired pipe inner-wall location.

In one embodiment, there is disclosed a method of transporting aproduced fluid through a pipe while limiting deposits at a desired pipeinner-wall location comprising providing a pipe having an inner surfaceroughness angle root-mean-square of less than 9 degrees at said desiredpipe inner-wall location, forcing the produced fluid through the pipe,wherein the produced fluid has a wall shear stress of at least 400 dyneper centimeter squared at said desired pipe inner-wall location.

In one embodiment, there is disclosed a method of calculating optimalshear stress in a pipeline system comprising providing a pipe having aninner surface roughness Ra of less than 5 micrometers, forcing anproduced fluid through the pipe at operating temperature, and increasingthe pipe's inner wall shear stress value until no wax deposits areformed on the inner wall.

In one embodiment, there is disclosed a method of transporting aproduced fluid through a pipe and forming deposits that require lessforce to pig and that produce a slurry when pigged comprising providinga pipe having an inner surface roughness Ra less than 3 micrometers,forcing the produced fluid through the pipe, wherein the produced fluidhas a wall shear stress of at least 1 dyne per centimeter squared in atleast a portion of the pipe, and providing a non-metallic, over-sized,compliant pig. In some embodiments, the pig comprises a bypass pig,wherein the pigging results in a diluted slurry of the fluid and thedeposits.

In one embodiment there is disclosed a method to prevent deposits on theinner wall of a pipe, tubing, pipeline, flowline, and/or well tubing(hereafter referred to as pipeline or pipe) during production andtransportation of produced fluids, for example in pipelines used in deepwater, where the problem of deposition is common due to the low ambienttemperature of the environment surrounding the pipeline.

As produced fluids are transported, solids may precipitate and depositon the pipeline wall. For example, paraffinic constituents of crude oilscan precipitate when the crude oils are cooled below a criticaltemperature (hereafter referred to as wax appearance temperature). Solidparaffin (sometimes designated as wax) that is transported to thepipeline wall or wax forming at the pipe wall may stick to the wall andover time the wax may reduce the pipe cross sectional area that isavailable for flow. The temperature at which wax comes out of solutionvaries from one crude or condensate to the next, with some crudes orcondensates dropping out of solution some paraffinic components attemperatures as high as 55° C. One solution to keep wax from forming ona pipeline wall is to keep the temperature in the transport pipelineabove the wax appearance temperature to keep the wax from depositing onthe pipe wall or even creating a wax plug.

In one embodiment, there is disclosed an alternative solution to keepdeposits from forming on a pipeline wall whereby solids are allowed todrop out of the production fluids but discouraged from adhering to thepipe wall and forming plugs. If solids are allowed to drop out butprevented from adhering to the pipe wall, the bulk fluid may continue toflow as a slurry with suspended solids. This can be accomplished bymaking the inside walls of the transport pipes smoother than the wallsof pipe normally used in subsea flowlines and pipelines eithermechanically, with coatings, and/or with electro-polishing, and bycontrolling the transport rate so as to provide a critical wall shearstress within the pipeline. In general, significantly eliminating thepipe roughness of the inner wall of the pipe will decrease the forcerequired to remove a deposit and in some cases decrease the rate ofdeposit buildup in the pipe. In some embodiments, the force required toremove wax, asphaltenes, and/or inorganic deposits like hydrates, salts,and/or scale, may be decreased by using a smooth pipe wall.

Lowering the wax deposition rate in pipelines may also lessen the neededfrequency of pigging (i.e. mechanical scraping). Flow rate capacity maybe maintained closer to the deposit-free capacity as a result of thedecreased flow obstructions and/or blockages created by deposits.

Referring now to FIG. 1, in one embodiment, there is illustrated remotesatellite well 12, which is connected to platform 14 with subseapipeline 10. Subsea pipeline 10 includes seafloor section 19 and risersection 18. Seafloor section 19 may be up to 30 or more kilometers long.Pipeline 10 may be composed of 12 meter joints of pipe welded together.It is common to form individual 48 meter segments of pipe, called quads(4 joints), which have been welded together as they are placed subsea toform pipeline 10. Seafloor section 19, which may be a kilometer or morebelow surface 28 of the ocean, terminates at sled 20. There is alsoillustrated an export pipeline 26 to transport oil or other productsfrom platform 14 to the shore. Platform 14 may include surfacefacilities 16, as are known in the art. The pipe traditionally used insubsea pipeline 10 and export pipeline 26 is referred to hereafter as“traditional pipe.” That is, traditional pipe is the standard pipe withrespect to roughness currently used for pipeline 10 and pipeline 26.

Referring to FIGS. 2 and 3, seafloor section 19 of the pipeline isillustrated. Seafloor section includes a passage 102 and a wall 104 thatencloses the passage 102. Wall 104 includes surface roughness 104 atypical of traditional pipe. Produced fluids may be enclosed within wall104 and passed through passage 102.

Referring to FIGS. 4 and 5, produced fluids have been passed throughpassage 102 of traditional pipe, where seafloor section 19 is exposed toa cold temperature environment, so that deposit 106 has been depositedon surface roughness 104 a. As deposit 106 is deposited, passage 102 isconstricted. In general, the larger the surface roughness 104 a, thegreater the strength of adhesion of the deposit 106 to the pipe wall.

In some embodiments, referring to FIG. 6, sea floor section 19 isillustrated which includes passage 202 enclosed by walls 204. Walls 204have surface roughness 204 a, which is significantly smoother thansurface roughness 104 a of traditional pipe.

Still referring to FIG. 6, as produced fluids are passed through passage202 at a rate for which the wall shear stress exceeds a critical value,few or no deposits are deposited on surface roughness 204 a. In general,a combination of smoother surface roughness 204 a and a wall shearstress above the critical value, leads to few or no deposition ofdeposits. For a very smooth pipe surface, the critical wall shear stressrequired to prevent deposits is low to moderate; as the pipe surfaceroughness increases, the critical wall shear stress required to preventdeposits increases. In pipes with roughness equal to that of traditionalpipe, the wall shear stress required to prevent deposits may be abovethat provided by normal operating rates.

In one embodiment, it is not required to use a pig to clean wax depositsfrom wall 204, because at the provided wall shear stress little or nowax deposits on surface roughness 204 a as compared to surface roughness104 a of traditional pipe.

In one embodiment, it is not required to use a pig to clean wax depositsfrom wall 204 as often as it is required to clean wax deposits 106,because at the provided wall shear stress little or no wax deposits onsurface roughness 204 a as compared to surface roughness 104 a oftraditional pipe.

FIG. 8 is a magnified view of a perfectly smooth surface. Thestreamlines of the flow are parallel to the surface. When the flowpasses around a deposit, the drag on the deposit is in the direction ofthe flow and parallel to the contact surface between the deposit and thewall. This flow-wall configuration applies the largest shear stress atthe deposit-wall interface and consequently is the most efficientconfiguration for preventing or removing deposits.

FIG. 9 is a magnified view of surface roughness 104 a of traditionalpipe. With such a rough surface, the flow streamlines do not follow thesurface and vortices are produced as shown on the left side of FIG. 9,where the flow over a “peak” of a rough surface generates vortices inthe downstream valley. These vortices may apply a weak and incoherentdrag on deposits. This drag is generally not parallel to thedeposit-wall contact. Because of this, deposits are apt to build in thevalleys. Once deposits fill a valley, the deposit may be anchored to thewall over the entire valley surface area and may become more difficultto remove. Consequently, surface roughness and flow rate play a largerole in determining when and where deposits form and when and where theyare removed.

Surface roughness is quantified in several ways. In ASME B46.1-2002,herein incorporated by reference, “Surface Texture (Surface Roughness,Waviness and Lay),” Ra is defined as the arithmetic average of theabsolute values of the profile height deviations over the evaluationlength and measured from the mean line. Ra is the most commonly usedroughness parameter in surface finish measurement. Another measure ofthe surface roughness is the root-mean-square of the angle (relative tohorizontal) distribution, α_(rms), along the surface. Another measure ofthe surface roughness, Rti, is the local vertical distance to each pointi from the lowest valley in the sample interval. Another measure of thesurface roughness is the root-mean-square of the Rti for a single samplelength, Rti_(rms).

FIG. 10 shows the wall profiles for four pipes. The horizontal axis (x)shows distance (in centimeters (cm)) along the plane of the meansurface, and the vertical axis (z) shows deviation in height (inmicrometers) from the mean surface. Above the x-axis from 0.0 inch to0.29 cm is shown the height relative to the surface mean for Pipe A, acommercial stainless steel traditional pipe with a roughness typical ofpipes used in subsea pipelines and flowlines. To the right of the datafor Pipe A in FIG. 10 are data for smoother pipes. Above the x-axis from0.29 cm to 0.65 cm is shown z for Pipe B, a commercial stainless steeltube. Above the x-axis from 0.65 cm to 0.98 cm is shown z for Pipe C, acommercial stainless steel tube with a smaller roughness, marketed tohave a roughness Ra of 0.25 micrometers or less. Above the x-axis from0.98 cm to 1.3 cm is shown z for Pipe D, a commercial stainless steeltube with an even smaller roughness, marketed to have a roughness Ra of0.125 micrometers or less. The difference in variation in z between PipeA, the traditional pipe, and Pipes B-D is very great.

FIG. 11 shows the Rti distributions for the four pipes shown in FIG. 10.FIG. 12 shows the angle (α) distributions for the said four pipes shownin FIG. 10. The Ra values and root-mean-square angle of thedistributions and the root-mean-square Rti for the said four pipes arelisted in Table 1, below. Pipe A, the traditional pipe, has roughnessmeasures that are quite different from those of Pipes B-D, the smoothpipes. TABLE 1 Values of Surface Roughness Parameters PipeRoot-Mean-Square Root-Mean-Square description Ra Angle Rti PipeA >60 >13 >175 Pipe B 25 6 150 Pipe C 2.5 4 25 Pipe D <2.5 <2 <8

Traditional pipe, the current standard for pipeline 10 and pipeline 26,may have an absolute surface roughness Rt of about 50, or 75 micrometersor higher and an α_(rms) of about 13 degrees or more as purchased from asupplier. Rt, similar to Rti defined earlier, is the longest verticaldistance from peak to valley over a measured length.

In some embodiments of this invention with moderate to high wall shearstress, suitable smooth pipeline 10 or pipeline 26 has a surfaceroughness 204 a Ra of less than about 25 micrometers Ra, or less thanone-half the surface roughness Ra of standard steel pipe 104 a.

In some embodiments of this invention with moderate to high wall shearstress, suitable pipeline 10 or pipeline 26 has a surface roughness 204a α _(rms) of less than about 9 degrees, or less than two-thirds of thesurface roughness α_(rms) of standard steel pipe 104 a.

In some embodiments of this invention with moderate to high wall shearstress, suitable smooth pipeline 10 or pipeline 26 has a surfaceroughness 204 a Ra of less than about 15 micrometers Ra, or less thanone-fourth the surface roughness Ra of standard steel pipe 104 a.

In some embodiments of this invention with moderate to high wall shearstress, suitable pipeline 10 or pipeline 26 has a surface roughness 204a α _(rms) of less than about 7 degrees, or less than about one-half ofthe surface roughness α_(rms) of standard steel pipe 104 a.

In some embodiments of this invention with moderate to high wall shearstress, suitable smooth pipeline 10 or pipeline 26 has a surfaceroughness 204 a Ra of less than about 10 micrometers Ra, or less thanone-sixth the surface roughness Ra of standard steel pipe 104 a.

In some embodiments of this invention with moderate to high wall shearstress, suitable pipeline 10 or pipeline 26 has a surface roughness 204a α _(rms) of less than about 6 degrees, or less than one-half of thesurface roughness α_(rms) of standard steel pipe 104 a.

In some embodiments of this invention with small to high wall shearstress, suitable pipeline 10 or pipeline 26 has a surface roughness 204a Ra of less than about 5 micrometers, or less than one-tenth thesurface roughness Ra of standard steel pipe 104 a.

In some embodiments of this invention with small to high wall shearstress, suitable pipeline 10 or pipeline 26 has a surface roughness 204a α _(rms) of less than about 5 degrees, or less than about one-third ofthe surface roughness α_(rms) of standard steel pipe 104 a.

In some embodiments, surface roughness 204 a and/or surface roughness104 a may be coated with a suitable coating to reduce the surfaceroughness value.

Referring now to FIG. 7, pipeline 19 is illustrated which includespassage 302 enclosed by walls 304. Walls 304 define passage 302 having adiameter of 2R 306, or a radius of R. A portion of passage 302 has alength L 308 from point 310 to point 312. Pressure is P1 at point 310,and pressure is P2 at point 312. The pressure drop along length L 308from point 310 to point 312. is (P1−P2). The cross-sectional area ofpassage 302 is πR². The force across the fluid in passage 302 from point310 to point 312 is (P1−P2)(πR²). This force is equal in magnitude andopposite in direction to the total resistance at the wall in passage 302from point 310 to point 312. The total resistance at the wall is thewall shear stress T times the wall-fluid interface area in passage 302from point 310 to point 312, which area is 2πRL. Equation 1 shows thatthe force due to the wall shear stress equals the force required to movea fluid through passage 302:(P1−P2)(πR ²)=(τ)(2πRL)  (1)Solving for τ from equation 1 yields:(τ)=((P1−P2)(R))/(2L)  (2)

In some embodiments, produced fluids passing through pipeline 10 orpipeline 26 have a wall shear stress at wall 204 of at least about 1dyne per centimeter squared.

In some embodiments, produced fluids passing through pipeline 10 orpipeline 26 have a wall shear stress at wall 204 of at least about 20dyne per centimeter squared.

In some embodiments, produced fluids passing through pipeline 10 orpipeline 26 have a wall shear stress at wall 204 of at least about 100dyne per centimeter squared.

In some embodiments, produced fluids passing through pipeline 10 orpipeline 26 have a wall shear stress at wall 204 of at least about 400dyne per centimeter squared.

In some embodiments, in order to calculate the optimal flow rate forcrude oil or condensate flowing through pipeline 19, a pipeline having asurface roughness less than about 200 microinches is selected and testedwith the crude oil that will be pumped through it in a test facility,where the crude oil is cooled in a temperature range at which the crudewill be transported through pipeline 10 or pipeline 26. The flow rateand/or the wall shear stress is then increased until there is either nodeposition, or the equipment is not able to produce a higher flow rate.If the equipment is not able to produce a higher flow rate, a smootherpipe may be selected such as a pipe having a surface roughness less thanabout 100 microinch, then the flow rate and/or the wall shear stress maybe increased until such time there is no wax deposition or the equipmentcan not pump any faster, and smoother pipes may be tested, such as apipe having a surface roughness less than about 15 micrometers, untilsuch time as a smooth pipe is found which produces little or no waxdeposition under the operating conditions.

Different fluid systems have different deposition tendencies and requiredifferent combinations of roughness and wall-shear-stress to avoiddeposits. Nonetheless, the roughness necessary to prevent deposits forproduced fluid streams with wall shear stress corresponding to the upperlimit of practical production rates is much smaller than the roughnessof traditional pipe. For streams with smaller wall shear stress, theroughness necessary to prevent deposits is even smaller.

Those of skill in the art will appreciate that many modifications andvariations are possible in terms of the disclosed embodiments,configurations, materials and methods without departing from theirspirit and scope. Accordingly, the scope of the claims appendedhereafter and their functional equivalents should not be limited byparticular embodiments described and illustrated herein, as these aremerely exemplary in nature.

EXAMPLE

A flow loop for deposition testing was used. Test sections withdifferent inner-wall roughness were installed. Deposition tests wereconducted with a 6-day period with temperature-controlled pumping of awaxy crude oil from a deepwater field in the Gulf of Mexico. Summaryresults are shown in FIG. 13. In FIG. 13, “White” diamonds denote a PASSin a deposition test (i.e., zero or insignificant deposition), “Gray”triangles denote a MARGINAL result, and “Black” diamonds denote a FAIL(i.e., significant and quantifiable deposition). The x value is the Raand the y value, wall shear stress, is calculated from fluid properties,flow rates, and pipe diameter. As FIG. 13 indicates, the said smoothPipes B-D used in the test section of the flow loop showed significantreduction in deposition compared to smooth Pipe A (test FAIL). It shouldbe noted that Pipe B is considerably smoother than Pipe A, traditionalpipe. As FIG. 13 further indicates, the said smooth Pipe D used in thetest section of the flow loop has no or insignificant amount of deposit(test PASS). The data of FIG. 13 demonstrate the reduction in depositionin pipe with smaller Ra roughness and higher wall shear stress.

Other tests were conducted in the flow loop for deposition testing inwhich deposits were formed in a pipe much smoother than a traditionalpipe but not smooth enough to prevent deposits from forming. The pipeswere then pigged, and data were collected on the pigging and resultingpigged stream. Some of these data are shown in FIG. 14. The force(directly related to test section differential pressure, dP) required topig the deposit from the “Polished Pipe” wall was significantly smallerthan that used for pigging deposits formed in a similar test with the“Standard Pipe.” Furthermore, the pigged stream of the smooth pipeproduced a slurry, whereas the pigged stream of the Traditional Pipeproduced a viscous agglomeration of wax and occluded oil.

1. A system for producing and transporting crude oil, comprising: a well for producing the crude oil; a processing facility for processing the crude oil; and a pipeline for traversing at least a portion of the distance between the well and the processing facility, wherein at least a portion of the pipeline travels through an atmosphere having a temperature less than 20 C, wherein the pipeline comprises a surface roughness on its interior surface less than 0.025 mm.
 2. The system of claim 1, wherein the atmosphere has a temperature less than 15 C.
 3. The system of claim 1, wherein the atmosphere has a temperature less than 10 C.
 4. The system of claim 1, wherein the surface roughness is between 0.025 mm and 0.0025 mm.
 5. The system of claim 1, wherein the surface roughness is between 0.025 mm and 0.01 mm.
 6. The system of claim 1, wherein the surface roughness is between 0.01 mm and 0.0025 mm.
 7. A method of producing and transporting crude oil, comprising: extracting crude oil from a well; placing the crude oil in a pipeline to transport the crude oil away from the well; wherein at least a portion of the pipeline travels through an atmosphere having an ambient temperature less than 20 C; and wherein the pipeline has a surface roughness less than 0.025 mm on an interior surface.
 8. The method of claim 7, wherein the atmosphere has a temperature less than 15 C.
 9. The method of claim 7, wherein the atmosphere has a temperature less than 10 C.
 10. The method of claim 7, wherein the surface roughness is between 0.025 mm and 0.0025 mm.
 11. The method of claim 7, wherein the surface roughness is between 0.025 mm and 0.01 mm.
 12. The method of claim 7, wherein the surface roughness is between 0.01 mm and 0.0025 mm.
 13. A method of transporting a produced fluid through a pipe while limiting deposits at a desired pipe inner-wall location comprising: providing a pipe having an inner surface roughness Ra less than 2.5 micrometers at said desired pipe inner-wall location; and forcing the produced fluid through the pipe, wherein the produced fluid has a wall shear stress of at least 1 dyne per centimeter squared at said desired pipe inner-wall location.
 14. The method of claim 13, wherein the inner surface roughness Ra is less than 1 micrometer at said desired pipe inner-wall location; and wherein the wall shear stress is at least 20 dyne per centimeter squared at said desired pipe inner-wall location.
 15. The method of claim 13, wherein the inner surface roughness Ra is less than 1.5 micrometers at said desired pipe inner-wall location; and wherein the wall shear stress is at least 100 dyne per centimeter squared at said desired pipe inner-wall location.
 16. The method of claim 13, wherein the wall shear stress is at least 400 dyne per centimeter squared at said desired pipe inner-wall location.
 17. The method of claim 13, wherein the pipe comprises an inner surface roughness angle root-mean-square of less than 5 degrees at said desired pipe inner-wall location.
 18. The method of claim 13, wherein the pipe comprises an inner surface roughness angle root-mean-square of less than 6 degrees at said desired pipe inner-wall location, and wherein the wall shear stress is at least 20 dyne per centimeter squared at said desired pipe inner-wall location.
 19. The method of claim 13, wherein the pipe comprises an inner surface roughness angle root-mean-square of less than 7 degrees at said desired pipe inner-wall location, and wherein the wall shear stress is at least 100 dyne per centimeter squared at said desired pipe inner-wall location.
 20. The method of claim 13, wherein the pipe comprises an inner surface roughness angle root-mean-square of less than 9 degrees at said desired pipe inner-wall location, and wherein the wall shear stress is at least 400 dyne per centimeter squared at said desired pipe inner-wall location.
 21. A method of calculating optimal shear stress in a pipeline system comprising: providing a pipe having an inner surface roughness Ra of less than 5 micrometers; forcing an produced fluid through the pipe at operating temperature; increasing the pipe's inner wall shear stress value until no wax deposits are formed on the inner wall. 